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| Titel |
Tracking isotopic signatures of CO2 at the high altitude site Jungfraujoch with laser spectroscopy: analytical improvements and representative results |
| VerfasserIn |
P. Sturm, B. Tuzson, S. Henne, L. Emmenegger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 7 ; Nr. 6, no. 7 (2013-07-12), S.1659-1671 |
| Datensatznummer |
250017919
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| Publikation (Nr.) |
 copernicus.org/amt-6-1659-2013.pdf |
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| Zusammenfassung |
We present the continuous data record of atmospheric CO2 isotopes measured
by laser absorption spectroscopy for an almost four year period at the High
Altitude Research Station Jungfraujoch (3580 m a.s.l.), Switzerland. The mean
annual cycles derived from data of December 2008 to September 2012 exhibit
peak-to-peak amplitudes of 11.0 μmol mol−1 for CO2,
0.60‰ for δ13C and 0.81‰ for δ18O. The
high temporal resolution of the measurements also allow us to capture variations
on hourly and diurnal timescales. For CO2 the mean diurnal peak-to-peak
amplitude is about 1 μmol mol−1 in spring, autumn and winter
and about 2 μmol mol−1 in summer. The mean diurnal
variability in the isotope ratios is largest during the summer months too,
with an amplitude of about 0.1‰ both in the δ13C and
δ18O, and a smaller or no discernible diurnal cycle during the
other seasons. The day-to-day variability, however, is much larger and
depends on the origin of the air masses arriving at Jungfraujoch. Backward
Lagrangian particle dispersion model simulations revealed a close link
between air composition and prevailing transport regimes and could be used to
explain part of the observed variability in terms of transport history and
influence region. A footprint clustering showed significantly different
wintertime CO2, δ13C and δ18O values depending on the
origin and surface residence times of the air masses.
Several major updates on the instrument and the calibration procedures were performed in order to
further improve the data quality. We describe the new measurement and
calibration setup in detail and demonstrate the enhanced performance of the
analyzer. A measurement precision of about 0.02‰ for both isotope ratios has
been obtained for an averaging time of 10 min, while the accuracy was estimated to be 0.1‰,
including the uncertainty of the calibration gases. |
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